In the related art, there is a semiconductor device in which a mounting area of the device is reduced by stacking and connecting substrates having semiconductor elements and integrated circuits provided thereon and/or therein. Although such a stacked semiconductor device reduces the required planar mounting area in a length direction and a width direction, in comparison with the case in which substrates are mounted side by side in one plane, reduction in a size in a stacked semiconductor device in the thickness direction is also required.